Field of Invention
This invention pertains generally to the detection of pesticides and other analytes and, more particularly, to a portable, handheld instrument and method which are particularly suitable for detecting pesticides on produce.
Related Art
Organic farming has been one of the fastest growing segments of American agriculture in recent years, and many people prefer organic produce because of its superior taste and quality. Organic farmers are not allowed to use synthetic pesticides or fertilizers, and organically grown produce contains significantly lower levels of pesticide residues than conventionally grown produce. With its more stringent growing requirements, popularity among consumers, and relatively limited availability, organic produce generally commands a higher price than other fruits and vegetables.
Produce is currently checked for pesticide residue by sending a sample of the fresh produce to a laboratory for analysis, which often requires several days to obtain a result.
In conventional lab testing, the mass of the sample is measured, the sample is ground up, and the mass of the analyte is then measured as a fraction of the sample mass, in parts per million (PPM). In another type of measurement known as dislodgeable foliar residue (DFR) measurements, the analyte is washed off the sample with a solvent, the mass of analyte is measured in the solvent, and the concentration is reported in mass per unit area of sample. DFR measurements are normally used in testing for worker safety, rather than safety for human consumption.
Heretofore, there have been some attempts to provide portable instruments for checking produce for the presence of pesticide residue through fluorescence spectroscopy in the field using an aqueous sample which is placed in a cuvette and analyzed in a spectrometer. While such instruments avoid the need to send the sample to a laboratory, the use of the aqueous sample is still time consuming and cumbersome.
U.S. Pat. Nos. 7,304,741 and 7,400,405 disclose portable, self-contained instruments which can be pointed at a target to detect the presence of pesticide residue instantly and without contact with the produce. Those instruments can be used in the field and in other locations to determine pesticide content.